Mechanical lock for railroad track switches



March 21, 1961 N. D. PRESTON MECHANICAL LOCK FOR RAILROAD TRACK SWITCHES Filed 000. 8, 1956 FIG.|. [3 n H m F1 F] W??? R TI TI F'II'T INVENTOR. NDPRESTON HIS ATTORNEY United; sees atent gOfice IVIECHANICAL LOCK FOR RAILROAD TRACK SWITCHES Neil D. Preston, Rochester, N.Y., assignor to General Railway Signal Company, Rochester, N.Y.

Filed Oct. 8, 1956, Ser. N0. 614,685

2 Claims. or. 246-161) This invention relates to switch locking devices for railroads, and more particularly pertains to an all mechanical switch lock for limiting the hand operation of a railway track switch subject to mechanical release by a train.

In a railway signalling practice, many main line track switches are power operated by switch machines which contain their own means for the electrical locking of the track switch. However, in some instances it is necessary for turnout tracks and commercial sidings to be connected to the main line by manually operated switches at some remote points not frequently used where it is not convenient and the expense does not warrant the use of power operated mechanisms. 'Such switches must nevertheless be protected against unwarranted use and resultant danger to main line traffic.

The present invention contemplates that such manually operated track switches be protected by a mechanical switch lock which can be operated to unlock the switch points immediately to allow entrance of a train into the siding but which can be operated only after a prescribed time interval to permit a train to leave the siding. In both instances, the main line signals will automatically be set at danger during the train movement into or out of the siding, but may be cleared while the train is in the siding.

Generally speaking, the mechanism of'the switch lock of the present invention is mounted in a suitable housing having a door which is padlocked and accessible only to an authorized trainman. Opening of the door permits manual operation of the switch lock and also operates door contacts in the usual manner to control the signals which govern train movement over the track switch on the main track. The actual locking means is of the conventional plunger type wherein a rod in the switch lock engages a hole in the switch point lock rod when in its closed main line position.

The mechanism is provided with two operating levers, one to set up the entrance movement into the switch and the other to set up the exit movement out of the switch onto the main line. In setting up an entrance movement, operation of the entrance lever operates a treadle to an active position above the rail. This treadle is located in advance of the track switch and next to a main line rail. As the train awaiting entry into the siding is obviously already on the main line, a short distance from the track switch, it merely advances to operate the treadle through its wheel tread or flange. Movement of the treadle conditions the locking mechanism for release of the locking means and the entrance lever and its associated treadle can then be restored to normal. The trainman can now manually unlock the lock rod by means of a crank operated locking plunger and throw the track switch to permit the train to advance into the siding. Movement of the crank operating locking plunger also restores the lock conditioning mechanism to normal. With the train fully in the siding and the main line clear, restoration of the switch machine and 2, the crank operated plunger to normal will permit closing of the mechanism casing door, whereupon the signals will be cleared again for the main line traflic.

In making an exit movement from a siding onto the main line, it is necessary to wait a predetermined time after setting the main line signals to stop in order to allow a train which may be in the block sufficient time to move beyond the track switch. When setting up an exit movement, operation of the exit lever conditions a clockwork time element device, after which the exit lever is latched in its operated position. After a predetermined time has elapsed the time element device will condition the locking mechanism for release and the exit lever may then be unlatched and restored to normal, thus restoring the time element device to normal also. The train-' man may now unlock the lock rod and throw the track switch in the same manner as previously described, thus permitting movement of the train to the main line. The presence of the train on the main line will automatically set the signal to danger at the entrance end of the block which it occupies, so that the switch lock door may now be closed and locked up.

An object of the present invention is the provision of an all mechanical switch lock having features which permit the quick entrance of a train into a siding, yet require the lapse of a time interval before a train can leave the siding, all accomplished without the use of batteries or other electrical means.

Another object of the present invention is the provision of a treadle operating means whereby the train awaiting entrance into the siding is normally used to condition the switch lock for quick entrance movements, but under no condition can a train leaving the siding afiect the operation of the switch lock releasing means.

Another object of the present invention is the provision of a treadle operating means for releasing the switch lock which requires conditioning by the trainnran prior to operation, so that under normal conditions of main 1 line traflic, the treadle operating means is positioned in a dormant condition.

A still further object of the present invention is the provision of an all mechanical switch lock mechanism which lends itself to adaptations including use of standard railroad practices and devices which are familiar in use, such as conventional door circuit controllers, time releasers and plunger switch type locking arrangements.

Other objects, purposes, and characteristic features of the present invention will be in part obvious from the accompanying drawing and in part pointed out as the description of the invention progresses.

In describing the invention in detail, reference will be made to the accompanying drawing which is shown diagrammatically rather than in detail, more for the purpose of illustration and understanding, and in which corresponding reference characters designate corresponding parts in the different views, and in which: 7

Fig. 1 is a simplified plan view of a typical switch layout showing the arrangement of the switch apparatus as used in connection with the switch lock of the present invention; and

Fig. 2 is a schematic perspective view of the switch lock mechanism of the present invention shown in operating relationship to the railroad track and track switch;

With reference to Fig. 1, there has been illustrated conventionally a railroad track and a track switch, the main rails 11 and 12 restingon and being fastened to the roadbed ties 13 in the usual way. The switch points 14 and 15 of the track switch are positioned between the main rails 11 and 12 and are fastened together by the usual tie rod 16 and switch rod 17. A lock rod 18 is connected to the tie rod 16 and cooperates with the switch lock SL. A connecting rod 19 is also fastened Patented Mar. 21, 19 1 to the tie rod 16 and operates the usual switch circuit controller SC. The hand throw switch machine SM is connected to the switch rod 17 by means of an operating rod 20. When the switch lock SL is in an unlocked condition, the switch machine SM may be thrown to operate the switch points 14 and to a turn-out position. Movement of the switch points 14 and 15 will operate the indication contacts of the switch circuit controller SC and position the lock rod 18 so it cannot again be locked up until the switch points 14 and 15 are returned to their main line position.

The switch lock SL is positioned on the ties 13 near the track switch to receive the lock rod 18 which passes through and is guided by a channel located in the base portion 22 of the switch lock casing 21. The casing 21 houses the switch lock mechanism and has a padlocked door 23 thereon which is accessible only to authorized trainmen. The mechanism is provided with three manually operated levers for functional operations, the entrance lever EN for initiating an entrance movement into the switch, the exit lever EX for initiating an exit movement out of the switch and a locking and unlocking lever L for actuating a locking plunger 24.

The entrance lever EN is pivotally mounted on an anchored pivot pin 25 and is connected to a track treadle T by suitable linkage so that when it is rotated to the right in a clockwise direction, it will position the treadle T for operation by a train wheel. The treadle T is located next to the main rail 12 a short distance in advance of the track switch and normally lies in a dormant position so that trains passing the switch will not affect its operation. In assembly, the entrance lever EN is provided with an extending arm 26 to which is pivotally connected a rod 27. The rod 27 is pivotally connected at its other end to one end of a lever arm 28 which is mounted on a pivot pin 29. The other end of the lever arm 28 is connected to a rod 39 which has its other end connected to a crank arm 31. The crank arm 31 is connected to a shaft 32 which is journaled in a tie mounted bearing bracket 33 and a boss located on the mechanism casing 21. Another crank arm 34 is connected at one end to the shaft 32 and the other end is pivotally connected to one end of a rod 35 which extends from the crank arm 34 along the track to the location of the treadle T. Due to its length the rod 35 may be rollably supported on standard type pipe carriers 36, as shown in Fig. 1. The other end of the rod 35 is connected to a. crank arm 37 which is mounted on a shaft 38. The shaft 38 is journaled in bearing brackets 39 and 40 which are fastened to the ties 13 and a plate 41 suitably mounted on the ties 13. Also mounted on the plate 41 is a stop plate 42 which is normally biased upward by a compression spring 43. As previously mentioned, the treadle T is not normally affected by a passing train but operation of the entrance lever EN will, through the linkage just described, position the treadle T in an upright position (as shown in dotted lines, wherein the lug portion 44 of the treadle T will rest on the spring biased stop plate 42. This spring 43 is of such strength that further operation of the treadle T by means of the entrance lever EN is prevented. Movement of the treadle T to its active position by other means is prevented when the casing door 23 is closed as a pin or lug 75 protruding from the door 23 stops movement of the lever arm 28.

Assuming now that there is a train on the main track waiting to enter the siding, its trainman may unlock the padlock 93 and open the door 23 and operate the entrance lever EN as described above. Opening of the door 23 will cause a spring biased door contact 45 to open and break the signal control circuit (not shown) and will also move a door lug 46 out of position away from a locking dog lever 4-7, thus releasing one end 48 of the lever 47 to permit movement in a counterclockwise direction. This lever 47 is pivotally mounted near its center on a bearing pin 49; However, movement of the entrance lever EN by the trainman has caused a cam portion 50 on the lever EN to be positioned directly over a locking dog portion 51 on the other end of the lever 47, so that the lever 47 is still locked against movement in a counterclockwise direction. Also, movement of the entrance lever EN has caused a counterclockwise movement of the lever arm 28. This lever arm 28 is provided with a trip arm 52 positioned so that the counterclockwise movement will cause it to move into a contacting position against a lug 53 on a release bar 54.

The release bar 54 lies in a vertical position and is slidably mounted in the casing lugs 55 and is spring biased to a downward position by a coil spring 56, the head 57 of the release bar 54 bearing against the top of the upper lug 55, thus limiting its downward movement. This release bar 54 is also provided with an extending arm 58 on one side and a recess 59 on its other side. This recess 59 is located slightly above a pivoted spring biased locking dog 60 which is positioned to enter the recess 59 upon an upward movement of the release bar 54. A fiat spring 61 hearing against the locking dog 60 provides the necessary bias. A compression spring 62 is positioned between the head 57 of the release bar 54 and the right-hand side of the lever arm 47.

As previously mentioned, operation of the entrance lever EN conditions the treadle T for operation by a train wheel. The trainman must now call for a short movement of the train toward the treadle T which will cause the leading train wheel to depress the treadle T against the opposition of the spring 43. Depression of the treadle T will cause further movement of the linkage arrangement and consequently further counterclockwise movement of the lever 28, so that its trip arm 52, which is bearing against the lug 53 will raise the release bar 54. Upward movement of the release bar 54 will tension the spring 56 and compress the spring 57 against the locking dog lever 47. However, this lever is still locked against movement because the locking dog portion 51 is bearing against the cam surface 50 as previously described. Also, upward movement of the release bar 54 will permit the locking dog 60 to enter the recess 59 wherein it will hold the release bar 54 in its release position. The locking dog 66 is journaled on the anchored pin 63 and is provided with an indicator arm 64 on one side of center and a trip arm 65 on the other side of center. The trip arm 65 is positioned to engage a projecting pin 66 located in a cam portion 67 of the lever L.

After movement of the train has depressed the treadle T and operated the release bar 54 to its release position, restoration of the entrance lever EN to its normal position will move the cam surface 50 away from the dog portion 51 of the lever 47 so that the trapped pressure of the spring 62 will now force a counterclockwise movement of the lever 47. This counterclockwise movement of the lever 47 will move its locking dog portion 51 upward out of engagement with a shoulder 68 located on the cam surface of the cam 67, thus unlocking the lever L for movement in a counterclockwise direction. In actual practice, the lever L and its associated cam portion 67 is provided with a suitable latching mechanism (not shown) which prevents a movement of the lever L in a clockwise direction when in its switch locking position.

This lever L has a crank 69 fastened to its shaft 70. A connecting rod 71 is connected between the crank 69 and the locking plunger 24- so that the locking plunger 24 moves in response to the movement of the lever L. The locking plunger 24 is slidably mounted in a boss 72 and when in its locking position it passes through a hole 73 in the lock rod 18. With the lever L now unlocked, the trainman operates the lever L in a counterclockwise direction to withdraw the locking plunger 24 from the hole 73 in the lock rod 18. This movement of the lever L also causes the projecting pin 66 of the cam portion 67 to contact the trip arm 65 of the lock dog 60, thus forcing the lock dog 60 from the recess 59 and permitting the coil spring 57 to restore the release bar 54 to its normal downward position.

With the lock rod 18 now unlocked, the trainman may manually operate the switch machine SM and throw the. track switch to a siding position to permit movement of the train from the main track into the siding. When the train is fully onto the siding track, the main line track may be restored to normal by reversing the track switch, whereupon the trainman will restore the lever L to normal to again lock up the lock rod 18 by means of the plunger 24. Movement of the lever L in a clockwise direction to its normal position will also permit the lock dog 51 to drop into position behind the shoulder 68, thus again locking up the lever L against a counterclockwise movement. Dropping of the lock dog 51 causes clockwise movement of the lever 47, thus raising the end 48 of this lever 47 above the position of the lug 46 on the door 23. The door 23 may now be closed and padlocked and the indicator 64 will be visible through the window 74 in the door 23, indicating that the track switch is normaland locked up. Also, with the door 23 closed, the door contacts 45 will also be cleared, thus clearing the signals again for main line trafiic.

It should be noted that during an entrance movement of a train into a siding from the main line, as just described, no operation of the exit lever EX is contemplated or required. Similarly, when making an exit movement from the siding onto the main line, no, operation of the entrance lever is required. However, in both movements, it is necessary to condition the release bar 54 and operate the lever L to unlock the track switch. In the case of the entrance movement, the unlock movement is facilitated by the operation of the treadle T due to the presence of a train; whereas the exit movement must be facilitated by a time element device TE because the track switch should not be thrown while there is a train present on the main line in the immediate block. Operation of the time element device will prevent immediate switch operation and allow a train time to clear the track switch if it has already entered the immediate block. Opening of the switch lock door 23 to operate the time element device TE will automatically set the block entrance signals to stop to prevent other trains from entering the block.

The exit lever EX is also pivotally mounted on the anchored pivot pin 25 and is connected to the time element device TE so that when it is rotated to the left the time element device TE is conditioned for a cycle of operation. This lever EX is provided with an extending forked arm 76 which cooperates with a rod 77 and a cam portion 78 for cooperation with the locking dog 51. The rod 77 has an enlarged head portion 79 at its upper end and a compression spring 80 is located on the rod 77 between the head portion 79 and the forked arm 76.

A collar 81 is pinned to the rod 77 at a location directly below the forked arm 76. The lower end of the rod 77 is pinned to one end of a crank arm 82 and this crank arm 82,'along with a ratchet gear 83and a driving gear 84, are all pivotally mounted on a pivot pin '85. The free end 86 of the crank arm 82 is adjustably connected to the ratchet gear 83 and is positioned to cooperate, when rotated clockwise, with the extending arm 58 of the release bar 54. A spring biased pawl 87 is pivotally mounted on the drive gear 84 in a position to coact with the teeth of the ratchet gear 83 so that a clockwise movement of the ratchet gear 83 will drive the drive gear 84 but a counterclockwise movement of the ratchet gear 83 will not cause a movement of the drive gear 84. The drive gear 84 meshes with an idler gear 88 to drive a gear train which is mounted in a housing 89, the gear train being provided with the usual escapement 90.

It can now be seen that a movement of the exit lever EX to the left will cause rotation about the pivot pin 25 and raise the forked arm 76, thus compressing the spring 80 and creating a space between the bottom of the forked arm 76 and the collar 81. The compressed, spring now provides the means for operating the time element device TE by forcing the rod 77 upward by virtue. of the force exerted against the head 79 of the rod 77. The.

upward movement of the rod 77 will rotate the crank arm 82 and its associated ratchet gear 83 and drive gear 84 in a clockwise direction at a certain speed as determined by the associated gear train 88 89 and its escapement device 90. The upward movement of the rod 77 will continue until such time as the collar 81 again bears against the bottom of the forked arm 76. The clockwise movement of the crank arm 82 will cause its free end 86 to come into engagement with the extending arm 58 of the release bar 54. The handle portion of the exit lever EX is pivotally mounted to provide lateral inward movement so that the exit lever EX may be locked in its operated position merely by forcing the handle inward, a pin 91 in the handle entering a hole 92 in the casing 21. With the exit lever. EX in its operated position and locked up, it is not necessary for the trainman to hold the handle while. the time element device TB is running out its time.

Assuming now that the trainman desires to initiate an exit movement to permit a train to leave a siding and enter onto the main line, he would unlock the padlock 93 and open the door 23 of the switch lock SL, thus breaking the signal control circuit at the door contacts 45 and setting the main line signals to stop to prevent other trains from entering that particular block. The exit lever may now be operated to its left hand position in a counterclockwise direction wherein it is held by reason of its handle pin 91 being'forced into the hole 92. With the exit lever EX in its operated position, the spring 80 will be compressed and the lever cam portion 7 8 will be directly over the locking dog portion 51 of the lever 47 so that immediate movement of the lever 47 is prevented. The upward bias of the compressed spring 80 will cause upwardmovement of the rod 77 and clockwise movement of the free end 86 of the crank arm 82 at a speed as limited by the time element device TE as previously described. As the lever arm 86 moves around in a clockwise direction, it will contact and raise the extending arm 58 of the release bar 54 thus causing upward movement of the release bar 54. 'Ihe upward movement of the release bar 54 will permit the spring biased locking dog 60 to enter the recess 59 and hold the release bar 54 in its release position. The adjusted position of the collar 81 and the crank arm 82 is such that the 1 time element device TB is now stopped.

With the release bar 54 now locked in its release position, the exit lever EX may be restored to its normal right-hand position. This restoring movement will force the rod 77 downward to rotate the lever arm 86 and its associated ratchet gear 83 counterclockwise to normal. The restoration of the exit lever EX has also moved, its cam portion 78 away from the locking dog portion 51 of the lever 47. The balance of the switch unlocking movement is now identical with the' operation described in connection with a train entrance movement.

In brief, with the release bar 54 now in its upward release position, the spring 56 is tensioned and the spring 62 is compressed. As the cam portion 78 of the exit lever EX is no longer holding the locking dog 51 down and the door lug 46 is out of position because the door 23 is open, the trapped pressure of the spring 62 will rotate the lever 47 in a counterclockwise direction, thus moving the locking dog 51 upward and releasing the cam portion 67 of the lever L. With the lever L now undocked, the trainman operates the lever L in a counterclockwise direction to withdraw the locking plunger 24 from the hole 73 in the lock rod 18. This movement of the lever L also causes the projecting pin 66 of the cam portion 67 to contact the trip arm 65 of the lock dog 60, thus forcing the lock dog 60 from the recess 59 and per- '7 mitting the coil spring 57 to restore the release bar 54 to its normal downward position.

With the lock rod 18 now unlocked, the trainman may manually operate the switch machine SM and throw the track switch to a siding position to permit movement of the train from the siding onto the main line. When the train is fully onto the main line track, the trainman may reverse the track switch back to normal main line traflic, after which he can restore the lever L to normal to again lock up the lock rod 18 by means of the plunger 24. Movement of the lever L in a clockwise direction to its normal position will also permit the lock dog 51 to drop into position behind the shoulder 68, thus again locking up the lever L against a counterclockwise movement. Dropping of the lock dog 51 causes clockwise movement of the lever 47, thus raising the end 48 of this lever 47 above the position of the lug 46 on the door 23. The door 23 may now be closed and padlocked and the indicator 64 will be visible through the window 74 in the door 23, indicating that the track switch is normal and locked up. With the door 23 closed, the door contacts 45 will also be closed, but the main line signals will not be cleared due to the presence of the train on the main line track in the immediate block.

From the foregoing it can be seen that the mechanical switch lock of this invention affords the desired features of safety and facility found in conventional switch locks, without the complication and expense of a local source of electrical power for operating a releasing track switch, or the usual electrically operated releasing track switch, or the usual electrically operated time element device. The particular organization of springs, detents and other parts, which may seem to be complex to perform simple functions, is purposely provided to insure a particular sequence of mechanical movements to assure a complete safe operation for each manipulation. For example, the trainman cannot operate the clockwork time element device to use up the desired release time, and leave the parts in such operated condition to be improperly used at some later time. On the contrary, after the train has operated the exit lever EX to cause the time element device to run out, this lever must be restored to its normal or initial condition, and in turn the clockwork mechanism, before the switch points can be actually unlocked. The same over and back sequence, utilizing spring tension trapped by detents or the like is characteristic of the general operation of this mechanical switch lock. This combination also atfords a check upon the integrity of the vital parts to a high degree. For example, the breakage or failure of the springs, connecting parts and the like is on the side of safety, because the sequence of over and back movements is interrupted, and the desired unlock, or relock and closing of the door to clear main track signals will not occur.

Having thus shown and described one specific form which the mechanical switch lock comprising the present invention can assume, it is desired to be understood that other structures could be substituted and that various detail mechanical changes or substitution-s could be made in the present structure, all without departing from the spirit of the present invention or the scope of the appending claims.

What I claim is:

1. A switch lock for a railway track switch comprising, a lock rod having one end connected to the points of the switch and extending outwardly away from the track, a locking mechanism normally locking said lock rod in a particular position, timing means, a first manually operable releasing means for initiating operation of said timing means and for releasing said lock mechanism only after the completed operation of said timing means, a normally inactive wheel detecting treadle located in advance of the track switch, separate manually operable 168118 for rendering said treadle responsive to the presence of a train, and means connected to said treadle for conditioning said first manually operable means for immediately releasing said locking mechanism independently of said timing means in response to the detection of the presence of a train by said treadle.

2. In a switch operating organization for railway track switches, a track switch normally set in one position for trafiic but also operable to a reverse position for traflic in that position, a locking mechanism located adjacent the track switch and operatively connected to the points of the switch for holding them in said particular position, manually operable means for releasing said mechanism to permit operation of the points of the track switch, said manually operable means having first and second initial positions and having a final position, a clockwork timing mechanism set into operation by the actuation of said manually operable means to its first initial position, said clockwork timing mechanism being normally efiective to prevent operation of said manually operable means to its final position until said clockwork timing mechanism has completed its operation after measuring a predetermined time, a train actuatable treadle means located in advance of said switch and normally being in a non-actuatable position, means connecting said manually operable means to said treadle for moving such treadle to a train actuatable position when said manually operable means is actuated to its second initial position, and means connecting said treadle to said manually operable means for permitting it to be operated from its second initial position to its final position in response to the presence of a train independently of the operation of said clockwork timing mechanism.

References Cited in the file of this patent UNITED STATES PATENTS 502, 149 Tew July 25, 1893 966,848 McManama Aug. 9, 1910 1,245,133 Taylor Oct. 30, 1917 1,326,298 Smart Dec. 30, 1919 2,027,702 Renshaw Jan. 14, 1936 2,365,344 Judge Dec. 19, 1944 

